Remote control apparatus



May 7, 1957 A. M. EaucKsEsAuMv 2,791,768

REMOTE CONTROL APPARATUS Filed Feb. 5, 1951 2 Sheets-.Sheet 1 M N Mmm .wh u m w BxNSQl MQQNQ @BENQ m m Y .oww om .Q w M I I o v T. gw m T wwwmk m A A Y B D bm.- N\w N/ v @m SUE fm h u n u. NSSSQ m muQM uuummmlm May 7, 1957 A. M. BUcKsBAuM 2,791,768

REMOTE CONTROL APPARATUS Filed Feb. 5, 1951 2 Sheets-Shee 2 INVENTOR.

BYARNoLo M. BucxsBAuM A T ToRNE Y 2,791,768 Patented May 7, 1957 REMOTE CONTROL APPARATUS Arnold M. Buchsbaum, Cedar Rapids, Iowa, assigner to Collins Radio Company, Cedar Rapids, iowa, a corn poration of iowa Application February 5, 1951, Serial No. 209,426

6 Claims. (Cl. 343-100) This invention relates in general to servomechanisms and in particular to apparatus which uses a radiant energy transmitter and receiver in the servo loop.

It is oftentimes desirable to control apparatus from a remote position and servomechanisms are often used for this purpose. The control station is connected by wiring to the remote controlled station. For example, it is often desirable to control the position of a gun from a remote position. The computations are made and the results in the form of shaft positions are fed to the gun through cables. Maintaining cable connections between the gun and the remote lcontrol position requires that the cables irst be laid and then protected from destruction by the enemy.

It is an object of this invention, therefore, to provide a control system which requires no electrical connections between the control and controlled point.

A further object of this invention is to provide a radiant energy transmitter and receiver which form a por tion of a servo loop. t

Yet another object of this invention is to provide a control mechanism in which both the controlling and the controlled station may be moved without destroying the control link. l

A feature of this invention is found in the provision for a transmitter which suppliesan output to a dipole antenna that is driven by amotor which runs in response to a control signal. A receiver is connected to a rotatable dipole antenna that is driven by a motor Which is in turn controlled by the output of the receiver.

Further objects, features, andvadvantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which:

Figure 1 illustrates the controlling and controlled apparatus of this invention; l

Figure 2 is a curve showingthe relationship between `the amplitude of the received signal and the angular vdisplacement of the transmitting and receiving dipoles;

Figure 3 is a detail diagram of the rotation circuit of the transmitter; and,

Figure 4 is a detail diagram-of the sensing circuit of the receiver.

Referring to Figure 1, a transmitter produces a radio frequency signal which might be, for example, 500 vmegacycles. The output of transmitter 10 is fed to a coaxial conductor 11. The end of conductor 11 engages a coaxial slip joint 12; A` second coaxial line 13 is connected to the opposite side of the slip joint 12 and xs electrically connected to the line 11 through the joint 12.

As shown in cutaway in Figure 1 the slip joint 12 has `emale portions for engaging the center and outer conductors of lines 11 and 13. The lines 11 and 13 might be made of copper, for example. A gear 14 is mounted on line 13.

The line 13 passes throughabearing 11S-which is mounted in the apex of a parabolic reilector 17. The line 13 extends through the bearing 16 and into the confines of the parabolic reflector 17 to terminate at the focal point. A dipole 18 is mounted transversely in the end 19 of the line 13 and is fed in a well-known manner to radiate the radio frequency energy received from the transmitter 1d. The dipole 18 is mounted atl approximately the focal point of the parabolic retlector 17 so as to obtain a maximum of radiated energy from the reector 17.

The gear 14 engages a gear 21 which is mounted on a shaft 22 of motor 23. A third gear 24 is mounted on a shaft 26 which is connected to a bridge-amplier 27.

The bridge-amplifier 27 supplies an electrical input to the motor 23, which might be a direct current motor. A control shaft 28 is connected to amplifier 27 and terminates in .a control knob 29. The amplifier 27 contains a bridge circuit an-d its output is governed by the angular difference between the shafts 26 and 28. For example, if the control knob 29 is rotated 30 degrees, the amplifier will give an output which is furnished to the motor 23 and it will run, thus turning gears 21 and 24 and the shaft 26 until the shaft 26 has rotated 30 degrees. The output of the amplifier will then be zero and the motor will stop. A servo loop is thus formed with the Vcontrol knob Z9 supplying the control information and the shaft 26 adjusting the balance of the amplifer until the output is zero. The bridge circuit may be anyrtype well known to those skilled in the art and for an example of one type, reference may be made to Patent No. 2,499,222. The conductor 13 is also geared to `motor 23 and thus, its angular position will follow the position of the knob 29. Means are provided for rotating the dipole 1S Vin response to rotation of a control knob 29.

TheV motor 23 turns in the same direction as control knob 29 forrthe reason that the bridge circuit of amplier 27 gives a negative output if knob 29 is turned clockwise, and a positive output if it is turned counterclockwise.

The motor 23 furnishes an output by means of a shaft 52 to a rotation circuit, designated generally as 51. The circuit 51 supplies an electrical output to transmitter 10, to modulate its output. For example, one kilocycle modulation `might be impressed on the transmitter output if motor 23 turns clockwise and two kilocycle modulation might be impressed thereon if motor 23 turns counterclockwise. The circuit 51 is shown in detail in Figure 3. The shaft 52 of motor 23, not shown, connects to a direct current generator 53 which gives an electrical output with a polarity depending on the direction of rotation of shaft 52.

A polarized relay 54 has its coil 56 connected to the output of generator 53 and its armature 57 is connected to ground. The armature 57 is movable to engage contact 58 or 59 when the relay is energized. Contact 58 is connected to a condenser C1 and contact 59 is connected to a condenser C2. An oscillator 61 is connected to the condensers C1 and C2 and is connected to ground. The condensers C1 and C2 are connected t0 the frequency control element of the oscillator and the oscillator 61 produces an output of l kilocycle, for example, when condenser Cr is connected to ground by armature 57. An output of two kilocycles, for example, will be produced by oscillator 61 when condenser C2 is connected to' ground by armature 57.

The output of oscillator 61'isV connected to transmitter 10 to modulate its output. Thus, the output of transmitter 10 is modulated by one or two kilocycles when the relay 54 is energized. Means are thus furnished for im- 3 pressing yon the transmitted signal a modulation indicative of the direction of rotation of the control knob 29.

A receiving antenna comprises a dipole 31 mounted in the end of a conductor 32 within a parabolic reflector 33. The conductor -32 passes through a bearing l34 and has mounted thereon a gear 36. The conductor 32 terminates Vin a coaxial slip joint 37 which is in turn connected to la conductor 38.

The conductors 32 and 38 are thus electrically connected together but may be rotated relative to each other. Theconductor 38 supplies an electrical input to a receiver 39. The receiver 39 `supplies an output to an amplifier '41 which in turn furnishes an input to a sensing circuit, designated generally as 62. The circuit 62 supplies an out- .vput to adirect current motor 42. The motor 42 has an out- Vput shaft 43 that carries a driving gear 44 thereon. The gear 44 meshes with the gear-36 to rotate the conductor 32 and dipole 31in response to rotationof the motor 42. The .gear 44 also engages a gear 446 mounted on a shaft 47 which has an indicator 48 mounted on its free end.

The energy transmitted from the parabolic reflector 17 will be polarized in a plane determined by the position of the dipole 18. Likewise, the reector 33 and dipole 31 will intercept the polarized energy and its output will be proportional to the 'angular difference between the dipole 31 and the plane of polarization of the transmitted energy.

This is more clearly vpointed out in Figure 2 wherein the amplitude of the received signal is plotted against the angular difference in polarization of the two antennas. Thus if the received energy at the antenna 33 is horizontally polarized and if the dipole 31 is set to its vertical position, no energy will be fed to the conductor 32. This is true because the response curve has a shape as shown in Figure 2. Thus when the dipole 31 is parallel to the transmitting dipole maximum reception will be obtained and when it is perpendicular, minimum energy will be received. This fact makes it possible to transfer a shaft position from the dipole 18 to the dipole 31. If the dipole 31 is rotated by the motor 42 until no energy is received, :a shaft position may be transmitted through the air between the dipoles 18 and 31. The receiver 39 gives an output whose amplitude is proportional to the energy received byv the dipole 31. The amplifier 41 amplifes its signal and supplies it to sensing circuit 62 which senses the direction of rotation of dipole 18 from the ymodulation on the incoming signal. The motor 42 receives an output from circuit 62. The indicator 48 which is geared to the motor 42 will be rotated the same amount as the conductor 32 and will thus indicate its position.

The sensing circuit `62 is shown Iin detail in Figure 4 and comprises a pair of tubes 64 and-66 which have their cathodes 67 and 68 connected to ground. The plate 69 of tube 64 is connected to the energizing coil of a relay 71 and the plate 72 of tube 66 is connected to the energizmg coil of a relay 73. The upper ends of relays 71 and 73 are connected together and to B+. An armature 74 is movable between contacts 76 and 77, and 78 and 79, respectively. The armature 74 is normally out of engagement with contacts 76, 77, 78 and 79 but upon energization of the relay 71, moves to engage contacts 77 and 76, respectively. Upon energization of relay 73 the armature 74 moves to engage contacts 78 and 79, respectively. A suitable direct current voltage as, for example, 28 volts, is supplied to contacts 76 and 77. Contacts 78 and 79 are electrically connected to contacts 76 and 77 but the leads are interchanged so that as armature 74 moves from one side lto the other a reverse in polarity will occur for the voltage supplied to contacts 81 and 82. The contacts 81 -and 82 are electrically connected to the direct culrent motor 42 and it will rotate in one direction when connected to contacts 76 and 77 and inthe opposite direction when connected to the contacts 78 and 79.

The output of amplifier 41 is supplied to the control grids 83 an'd84 'oftubes 64 and 66. A firstbattery E1 lhas its positive plate'connected to `ground and its negaafrontan f tive side connected to a tuned circuit comprising the .inductance VL1 and the capacitance C3. The opposite side of the tuned circuit is connected to the grid 83 of tube 64. The values of L1 and C3 may be selected, for example, so that the circuit is resonant at one kilocycle. The tube 64 is normally cut off and the value of the bias E1 may be chosen such that when l kilocycle is furnished from the amplifier 41 the tube 64 will conduct.

A second tun-ed circuit comprising indu-ctance L2 and capacitance C4 is connected between grid 84 of tube 66 and has its opposite side connected to the negative plate of a battery E2. The positive plate of the battery E2 is connected to ground. If the values of L2 and C4 are chosen so that they are resonant at two kilocycles the value of Ez maybe chosen so that the tube 66 will conduct when two kilocycle modulation is present in the input from amplifier 41 and will be biased to cut-off at all other times. This circuit will therefore control the direct current :motor 42 in a manner such that it will rotate in one direction Vwhen one .kilocycle modulation is received from the amplifier 41 and will rotate in the opposite .direction if two kilocycle modulation is received from the amplifier 41.

In operation 'itfis seen that the apparatus of this invention may be used to control a shaft position remotely by transmitting a .polarized radio signal and with no wires connected between the master and the slave positions. For example, the control knob 29 might be fed information as to the azimuth setting for a field artillery gun located a Vnumber of miles away. The control information fed to the control knob 29 will be radiated from the dipole 18 and received at the remote point by the dipole 31. The `dipole 31 will berotated by -its servo-mechanism until it is at right angles to the transmitting dipole 18. The indicator 48 might be connected to a motor control circuit for changing the azimuth of the gun so that the azimuth of the gun follows the position of the control knob '29.

It is seen that this invention provides means for transferrling a shaft position by utilizing the principle .that an antenna set at right angles to an incoming ,polarized wave will pick up no energy.

Although the invention has been described with respect to a preferred embodiment thereof it is not to be so limited as changes and modifications may be made therein which are withinthe full intended scope of the invention. For example, the dipole .31 might be rotated manually by an operator w'ho 'watches an output meter on the receiver 39 until the incoming signal is minimized. He then knows the .position of the transmitting dipole 18.

I claim:

l. A control system comprising, a rotatably mounted polarized transmitting antenna, a transmitter Supplying an electrical 'outputto Vsaidtransrnittng antenna, a bridge circuit receiving a control shaft input, a first driving means mechanically 'connected to said 'transmitting antenna and supplying a 'mechanical input to said bridge circuit, a .rotation circuit `'receiving a mechanical input from said 'first 'drivingrne'ans 'and comprising, a direct current generator mechanically connected to said`first driving means, a polarized relay receiving the output of said generator, frequency control means connected to said polarized relay, an A4oscillator connected to said frequency control means, and supplying an input to said transmitter `to modulate 'itin response to energization of said polarized relay.

v2. Ina controlsystem comprising, a rotatably mounted polarized receiving antenna, a receiver receiving the Aoutputof fsaid antenna, and driving means connected to said antenna, -a sensing circuit Vcomprising first and second electronic valves with their control grids receiving -an input from said receiver, a first -tuned circuit connected between the grid -of'the first electronic valve and ground,

a second tuned circuit connected between the vgrid 'o'fthe second electronic 'valve and lgrotintLa first relay connected in the plate circuit of said first electronic valve, a second relay connected in the plate circuit of said second electronic valve, said Erst and second relays mechani. cally connected to a reversing switch and said reversing switch supplying an actuating voltage to said driving means when the irst or second relays are energized.

3. Means for transmitting a polarized control signal comprising, a control shaft, a servo bridge circuit mechanically coupled to said control shaft, a driving means with its input electrically connected to the output of said bridge circuit, a rotatably mounted polarizing antenna mechanically coupled to said drive means, a rotation circuit with its input connected to said driving means to produce different frequency signals for each direction of rotation of said antenna, a transmitter connected to and modulated by the output of said rotation circuit, and the output of said transmitter connected to and radiated by said antenna in a polarized plane that corresponds to the rotational position of said control shaft.

4. Means for receiving and tracking polarized radiant energy comprising, a single rotatably mounted plane polarized antenna, a receiver receiving an input signal from said antenna, a sensing circuit capable of distinguishing different modulations on said input signal connected to said receiver, drive means connected to said sensing circuit and coupled to said antenna to drive it to a signal null position, and a shaft mechanically coupled to said driving means and responsive to said driving means for producing indicia of the position of said antenna.

5. A rotation circuit in a transmitter comprising, a driving means, a direct current generator receiving a shaft input from said driving means, a polarized relay receiving the output of said direct current generator, an oscillator supplying an output to said transmitter to modulate its output, frequency varying means connected to said oscillator, and said frequency varying means controlled by said polarized relay.

6. A rotation circuit in a transmitter comprising, a rotatable antenna, a direct current generator receiving a mechanical input corresponding to the rotation of said antenna and having output signals with a plurality of polarities, a polarized relay receiving an output from said generator, a variable oscillator, a frequency control element supplying an output to said transmitter to modulate its output, a first impedance connected to the frequency control element of said oscillator when said polarized relay is energized by signals of one polarity, and a second impedance connected to the frequency control element of said oscillator when the relay is energized by signals of the opposite polarity and a transmitter connected to said oscillator and modulated by said oscillator signal in response to the direction of rotation of said antenna.

References Cited in the file of this patentV UNITED STATES PATENTS OTHER REFERENCES Terman: Radio Engineering, 3rd edition, 1947, 515.

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